The present invention relates to an inkjet head. Conventionally, an inkjet printer which jets the ink onto the recording medium such as a sheet or plastic thin plate and records a predetermined image is proposed and in practical use. The inkjet printer has an inkjet head having a nozzle, when the ink is jetted to the recording medium from the nozzle while such an inkjet heads is moved in a predetermined direction, a predetermined image is recorded on the recording medium.
Hereupon, there is a case where the ink used for the inkjet printer is supplied to the head on a carriage from an ink supply vessel through an ink supply tube.
In this ink supply mechanism, in order to scan the carriage on which the head is mounted, an ink pressure supplied to the head is varied by the acceleration and deceleration or vibration. In this case, there is a problem that when the meniscus position of the nozzle of the head is dislocated, uneven density is caused and in the worst case, the meniscus is broken and the ink can not be jetted.
Further, in the conventional proposal for the resolution for such a phenomenon, there is a proposal by which the pressure variation at the time of ink supply is absorbed as a structure in which a damper is arranged on the upstream of the head as shown in Patent Document 1 (Tokkai 2000 No. 158868), Patent Document 6 (Tokkaihei 10 No. 193646), Patent Document 7 (Tokkaihei 11 2000 No. 34349). However, when there is piping between the damper and head, there is a problem that although it is minute, the variation is caused in the ink supply pressure by the mechanical vibration or acceleration and deceleration.
Therefore, conventionally, in order to prevent such a minute pressure variation, there is a structure in which the damper function is provided in the inside of the head.
For example, in Patent Document 2 (Tokkai 2001 No. 130004), a structure in which a shield structure air chamber is provided in the common ink chamber of the head and the damper function is given is disclosed. Further, in Patent Document 3 (Tokkai 2004 No. 114415), a structure in which the damper function is given by using a thin plate in the lamination head is disclosed. Further, in Patent Document 4 (Tokkaihei 7 No. 137262), a structure in which a groove is formed in the common ink chamber of the head, and separated from the air chamber by the film and the damper function is given is disclosed. In Patent Document 5 (Tokkaihei 7 No. 323548), a structure in which a gas holding chamber is formed adjoining the common ink chamber of the head and the bubble is accumulated by the electrolyzation and the damper function is provided is disclosed. In Patent Document 8 (Tokkai 2004 No. 226321), a head for bio-chip by which when the ink of the reservoir of the head is brought into contacted with the air, the down-sized pressure chamber can be structured, is disclosed.
As disclosed in the above Patent Documents 2, 3, 4, when a member such as the film is stood on the interface between the air chamber and the ink, the wash out of the air from the air chamber can be securely prevented. However, for forming such structure, because the new part or manufacturing process is necessary, further, the structure becomes complicated, a special design is necessary and there is a possibility that results in the cost-up or the reliability decrease.
Further, as disclosed in the above Patent Documents 5, 8, in a structure in which the air-liquid interface is formed by contacting the air with the ink, it is not simple that the air is stably accumulated in such a position, and a problem that the air-liquid interface does not exist by the suction movement for preventing the blinding of the nozzle, is generated.
Particularly, when the air is introduced into the common, ink chamber, because the air is not fixed in the common ink chamber, and can be freely moved, it enters into the pressure chamber, the accident that it often prevents the jetting of the ink is happened, or a problem that the air which is entered at a great pain is delivered, is generated.
Further, in the above structure in which the air-liquid inter face is formed by contacting the air with the ink, because in the air-liquid interface in which the air contacts with the ink, the air is dissolved in the ink. When a predetermined time passes, the air is diminished, there is a problem that the absorption effect of the pressure variation is loosed. The velocity in which the air dissolves is very slow, there also be a case where it takes a several months. It is not preferable because it results in the cost-up that the mechanism by which the air is newly supplied at such a span, is provided.
In any Patent Documents, there is no description relating to that the air is dissolved in the ink, and there is no disclose relating also to influence that it gives to the absorption effect of the pressure variation.
Further, as disclosed in the above Patent Document 5, in the structure that the air holding chamber is formed adjoining the common ink chamber of the head and that bubble is accumulated by the electrolysis and the air is supplied, the structure becomes complicated, and the complicate control of the timing that the bubble is generated by the electrolysis, is necessary. Further, there is also a problem that it does not function in the oil-based ink in which the gas is not generated by the electrolysis.
Further, in a structure in which the gas holding chamber is formed adjoining the common ink chamber of the head and the bubble is accumulated by the electrolysis and the air is supplemented as disclosed in the above Patent Document 5, the structure becomes complicate and the complicate control such as the timing at which the bubble is generated by the electrolysis becomes necessary. Further, there also is a problem that it does not function in the oil-based ink in which the gas is not generated by the electrolysis.